1. Technical Field
This invention relates generally to a medical device for percutaneously accessing a patient's air passageway, and more particularly, to a device for atraumatically dilating an opening in a tracheal wall and positioning a tracheal tube in said opening.
2. Background Information
The restoration of an adequate air passageway is the first critical step in maintaining the ability of a seriously ill or injured patient to breathe, or in performing resuscitation on a patient unable to breathe. Endotracheal intubation (the placement of a tube through the nostrils or mouth and into the trachea itself) is the preferred method for establishing an air passageway when the trachea, nostrils and/or mouth are free of obstruction. When such obstruction is present, however, endotracheal intubation is not possible, so that some other passageway for airflow must be established.
The most direct way to provide an air passageway under these circumstances is to form an opening in the tracheal wall, and once formed, to keep it open by inserting a tracheal tube. Conventional tracheal tubes generally include an open distal aperture and a circumferential inflatable cuff to provide a seal between the tracheal wall and the tracheal tube.
Several methods and devices are known for forming or enlarging an opening in a tracheal wall. Each method is subject to its own advantages and drawbacks. For example, tracheostomy and cricothyrotomy procedures have been performed by using a scalpel to make an incision in the neck. Such procedures entail a high degree of surgical skill to perform successfully, particularly since it is vital to locate and avoid unintentional severing of the blood vessels in the area. These procedures can even require the surgeon to cut through several blood vessels and ligate (tie) them to the trachea, in order to achieve an adequately large opening. The length of time needed to perform these procedures (often, on the order of half an hour) is poorly suited to emergency treatment, when prompt restoration of the air passageway is critical. Moreover, the use of a scalpel to fully form an opening potentially causes undue trauma to the tissues surrounding the opening, and can result in the formation of an unduly large or oversized opening in the soft tissue of the neck.
To minimize such trauma, it has been found desirable to initially incise only a small opening, and thereafter enlarge the opening with further dilation. For example, one technique for dilating an opening includes the use of a wire guide to facilitate the introduction of a dilator into the trachea. This technique involves the insertion of a needle and an over-the-needle catheter into the trachea. The needle is removed and the catheter replaced with a wire guide. A tapered, elongated, tubular dilator is positioned over the wire guide and introduced into the trachea. A drawback of this technique is that it requires the preliminary use of a scalpel to make an incision through the skin and cricothyroid membrane so that the needle can be inserted into the trachea. Even though intended to be performed in an emergency situation, the technique entails the sequential manipulation of several devices by the physician, which is time consuming and complicates the procedure.
Another procedure eliminates the use of the catheter and involves placing a wire guide through the needle itself. The opening formed by the needle is then dilated by the use of a device having a handle and a nose, the nose extending laterally from the axis of the handle. The nose has two jaws that spread apart for separating the tissue surrounding the opening, and the device is introduced into the trachea by positioning the elongated, tapered nose over the wire guide. While this type of device offers more powerful dilation than is possible with elongated tubular dilators, a problem with this device is that the unguarded nose must be inserted into the trachea with precision, and must be manipulated at an angle, in order to avoid perforating the posterior tracheal wall.
Another prior art technique for dilating an opening is the use of a tapered, elongated, tubular dilator, or a series of tapered dilators having increasingly larger diameters. Although such dilators are effective for forming a suitably-sized opening in the tracheal wall, each dilator presents a pointed distal end to the posterior tracheal wall when introduced into the trachea. The risk of injury to the trachea is compounded by the toughness of the tracheal membrane, which resists the introduction of medical devices. Introducing these elongated dilators requires the application of considerable force. Although a hydrophilic coating may be applied to the dilator to reduce the amount of force required to insert the dilator, a physician must still exert a downward force to push the dilator into the trachea, and yet avoid puncturing the posterior tracheal wall.
A prior art device described in U.S. Pat. No. 5,653,230, incorporated by reference herein, describes an apparatus and method for radially dilating a tracheal opening. This device permits the enlargement of an opening without risk of perforating the rear of the trachea by providing a polymeric inflatable balloon at the distal end of a catheter. The balloon is inflated to atraumatically dilate a portion of the tracheal wall to form the opening. Although this device is generally effective for avoiding the necessity for the downward or axial force required with many existing devices, the device is structured such that the balloon is deflated immediately following dilation, and is then advanced through the tracheal opening into the interior of the trachea before the tracheostomy tube is inserted into the opening. This leaves the dilated opening unsupported for a period of time. In some patients, this unsupported dilated opening is subject to shrinkage in diameter or even closure. Such action may cause difficulties when the tracheostomy tube is advanced into the opening, resulting in the necessity to re-dilate the opening or to apply a downward force to pass the distal end of the tracheostomy tube through the opening.
It would be desirable to provide an apparatus for forming and dilating an opening in a tracheal wall which is atraumatic, that is, which substantially avoids the trauma and damage to the tracheal wall encountered in many prior methods and devices. It would also be highly desirable to find such an apparatus which permits the enlargement of a tracheal opening without high risk of perforating the rear of the trachea.